STL file dimensions

I have created a simple part in Geomagic. When I save it as a STL file and then import it in Repetier to print, the size of the part is reduced significantly. The part is a simple round disc with a hole in the center. Outer diameter is 5/16 with a hole in the center of 1/8 and a thickness of 1/8. in order to bring it up to close to the correct size in Repetier I must enlarge it by 26 times its imported size. This gets it very close to the required dimensions.
Any suggestions would be much appreciated.
Thank you,
Leif

Check the STL output options for units - though from what I remember this could be clearer. Note that GD works internally in cm, which may or may not be important. You'll have to try changing units settings for STL output to get the behaviour you expect.

.STL files usually dont have a dimension type associated with them. The package you import them into will allocate inches or mm (or elephants) and you must find how to specify which you want at the import stage.